build_items.py

#!/usr/bin/env python3
"""Build GuardBench items: 20 patterns x 6 shapes.

Ground truth is set by the delta, not by judgement. The guard is always at distance from the
sink - a helper above, a decorator, a module constant, or a branch several lines up - because a
guard adjacent to its sink cannot be missed and that is exactly why FBE could not measure this.
"""
import json, ast, os, sys, hashlib
from collections import Counter

HERE = os.path.dirname(os.path.abspath(__file__))
sys.path.insert(0, HERE)
import build_items_v1 as V1
from patterns_v2 import P2
from covers_alt_v1 import COVERS_ALT

SHAPES = ["none", "covers", "covers_alt", "wrong_value", "irrelevant", "elsewhere"]
LABEL = {"none":"unsafe", "covers":"safe", "covers_alt":"safe",
         "wrong_value":"unsafe", "irrelevant":"unsafe", "elsewhere":"unsafe"}
WHY = {
 "none": "no guard is applied on this path",
 "covers": "the guard is applied to the tainted value and addresses the weakness",
 "covers_alt": "a second correct implementation, defended a different way",
 "wrong_value": "the guard is applied to a sibling value, not the one that reaches the sink",
 "irrelevant": "a guard is applied to the right value but does not address this weakness",
 "elsewhere": "the guard exists and is used by a neighbouring function, not on this path",
}

def build():
    out, seen = [], set()
    def add(name, cls, shape, code):
        h = hashlib.sha1(code.encode()).hexdigest()[:12]
        if h in seen: return
        seen.add(h)
        out.append({"id": f"{name}_{shape}", "pattern": name, "shape": shape,
                    "label": LABEL[shape], "vuln_class": cls if LABEL[shape]=="unsafe" else None,
                    "why": WHY[shape], "code": code})

    for fn in V1.P:                       # 8 v1 patterns, 5 shapes + covers_alt
        cls, *variants = fn(None)
        for shape, code in zip(["none","covers","wrong_value","irrelevant","elsewhere"], variants):
            add(fn.__name__, cls, shape, code)
        alt = COVERS_ALT.get(fn.__name__)
        if alt: add(fn.__name__, cls, "covers_alt", alt)

    for fn in P2:                          # 12 v2 patterns, 6 shapes
        cls, d = fn(None)
        for shape in SHAPES:
            if shape in d: add(fn.__name__, cls, shape, d[shape])
    return out

if __name__ == "__main__":
    rows = build()
    bad = []
    for r in rows:
        try: ast.parse(r["code"])
        except SyntaxError as e: bad.append((r["id"], str(e)))
    p = os.path.join(HERE, "items.jsonl")
    with open(p, "w") as fh:
        for r in rows: fh.write(json.dumps(r)+"\n")
    lab = Counter(r["label"] for r in rows)
    print(f"items: {len(rows)} -> {p}")
    print("patterns:", len({r['pattern'] for r in rows}))
    print("shape :", dict(Counter(r['shape'] for r in rows)))
    print("label :", dict(lab), f" safe share {lab['safe']/len(rows):.0%}")
    print(f"classes: {len({r['vuln_class'] for r in rows if r['vuln_class']})}")
    print(f"syntax errors: {len(bad)}")
    for i,e in bad[:6]: print("   ", i, e)